The present invention relates to a process and apparatus for filtering, and more particularly, for filtering ozone laden air in an ionographic imaging apparatus.
An ionographic imaging apparatus is generally a printer having an ion projection means for projecting ions upon a charge receptor surface having an ion generator, an inlet channel and an outlet channel connected to the ion generator, a source of transport fluid in communication with the inlet channel for delivering transport fluid to move ions through the outlet channel, and modulation means located adjacent the outlet channel for controlling the passage of ions therethrough to the charge receptor.
It is generally essential in such machines in commercial use to decompose and dissipate ozone to comply with machine ozone emission standards. Also, the accumulation of ozone in a machine can result in the degradation and deterioration of machine components.
It is well known in the art to filter ozone emissions. For example, U.S. Pat. No., 4,202,618 discloses a method to prevent ozone emission to a machine exterior. It is achieved by use of an activated carbon filter. A fan guides the contaminated air to the air filter. After passing through the filter, the air is eventually mixed with cooler air emitted from the electronics compartment of the machine.
U.S. Pat. No. 3,767,300 discloses a pollution control system for a photocopying machine. Contaminates are passed through a cold trap to produce a condensate which is mixed with the carrier liquid and water and separated out.
It is also known, as disclosed in U.S. Pat. No. 4,540,268, to use an ozone filter in a removable process kit in an electrophotographic copying apparatus. In particular, an air differential is provided by a fan to convey ozone laden air to a filter secured in the removable process kit.
Also, U.S. Pat. No. 4,401,385 to Katayama et al. and German Laid-Open Patent No. 3,026,969 disclose the use of an ozone filtering mechanism. U.S. Pat. No. 4,264,184 to Nishikawa et al. and U.S. Pat. No. 3,675,096 to Kiess disclose the removal of ozone by a catalyst device.
The above described prior art devices relate to electrophotographic copier devices, and, in general, require an independent source of fluid or air flow such as a fan to convey generated ozone to a suitable filter. This often requires separate ducting or channels for the necessary air flow path. The independent source of air and separating ducting can be relatively complex and expensive. It is an object, therefore, of the present invention to provide a simple and inexpensive means to filter ozone in an ionographic imaging apparatus, in particular, using the ionographic source of transport fluid and ionographic machine geometry to convey generated ozone to an ozone filter. Further advantages of the present invention will become aparent as the following description proceeds and the features characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.